rcu: create new rcu_access_index() and use in mce

The MCE subsystem needs to sample an RCU-protected index outside of
any protection for that index.  If this was a pointer, we would use
rcu_access_pointer(), but there is no corresponding rcu_access_index().
This commit therefore creates an rcu_access_index() and applies it
to MCE.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Zdenek Kabelac <zkabelac@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 5a05ef63eb4a..3385ea26f684 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1626,7 +1626,7 @@ out:
 static unsigned int mce_poll(struct file *file, poll_table *wait)
 {
         poll_wait(file, &mce_wait, wait);
-        if (rcu_dereference_check_mce(mcelog.next))
+        if (rcu_access_index(mcelog.next))
                 return POLLIN | POLLRDNORM;
         if (!mce_apei_read_done && apei_check_mce())
                 return POLLIN | POLLRDNORM;